Sam Mendes: 'So much of this job is to instil confidence. You need to be the leader.' Photograph: Bohdan Cap

Sam Mendes, director of Skyfall, hesitates. He is thinking about James Bond. It is, after all, partly thanks to him that Bond has recently acquired a psyche. But his case history is not easy to sum up. After a moment, he laughingly says that, were Bond on the couch, he would tell him: "You have many demons. If I were to put you into Freudian analysis, you would be there for the next 200 years. What I strongly advise is a change of career. Why not run a small shop?"

This is not advice anyone is about to give Mendes himself. His charmed career has reached new heights. He started out as a 24-year-old dynamo directing Judi Dench in the West End. He founded and ran the Donmar theatre for 10 years from 1990. He won five Oscars for American Beauty in 1999 when he was not even 35. And he directed a film of America's dark suburban novel Revolutionary Road , starring his ex-wife Kate Winslet. But Skyfall is something else again. It broke UK box office records in its first week – taking £37.2m – and is now Britain's highest-grossing film ever. Now the only question is whether Mendes is going to make the sequel.

At 47, he has a young face – his grey hair and beard in contrast to his vibrancy. He is bearlike in his shaggy black jumper. A comfortable, vigorous, jovial presence filling the large sitting room in which we meet – part of his Covent Garden production company. "It's not true that I've worked out a new plot for Bond. Nor have I made any commitment to another Bond movie. I have said that I've put everything I wanted into this film. The idea I can simply start again makes me feel physically ill. I need to get back to theatre, spend more time at home and then… and then it might be someone else's turn." The truth is Skyfall will be a hard act to follow no matter who is in the driving seat.

Above all, Mendes needs a good story: "Directing depends upon a story's rhythm – a good story should breathe in and out." Or, in Bond's case, hold its breath? He explains that Skyfall's opening 10 minutes, involving three Turkish locations, took more than two months to film. He talks about shooting in "the disused tube platforms under Charing Cross in stygian darkness". He jokes: "When I said 'yes' to a Bond movie, I pictured South America, the Andes, a tropical island. And what was I given? F-ing London Underground …" The reward for filming there? "Black snot." But wasn't Shanghai, at least, as dazzling as his film made it look? He smiles and shakes his head.

Making the film was exhausting, "like making four movies in one". It was, he says, half pleasure, half pain. And daunting? How would Mendes answer the question Bond is asked: what do you know about fear? "Quite a lot – I am a good dissembler. So much of this job is to instil confidence. You need to be the leader. If you are scared, you have to hide it – it is not useful." A Bond film is "frightening" because "one's personality could be consumed by the machine". He adds: "I am the opposite to Bond. I'm a physical coward. I don't enjoy firing a gun. And I drive very slowly."

But the film has been liberating too. For once, he has not been worried about the critics (perhaps his Cambridge education or his parents – his Portuguese Trinidadian father was a university literature professor and his mother is an author – can be held responsible for his having taken them too seriously in the past). "I stopped thinking about threading the needle between genres. I have made a Beckettian war movie (Jarhead), a $100m gangster movie like an arthouse film (Road to Perdition) and relationship dramas that are dark as they come (Revolutionary Road). It was nice to say: my sole job here is to tell a great story."

And when his crowd-pleaser pleased the critics, he saw a lesson in it. I ask if using Adele was his idea? He says it was a joint thing and adds: "She sat on that sofa over there." He remembers how worried she was about writing a Bond theme tune as her lyrics are always very personal. He explains: "I told her to write a love song." When she did, he was over the moon: "Coming in from the country to shoot, I listened to her song solidly for two hours." But he is also tickled pink, it would appear, at having made a middle-aged Bond film: "This Bond is about a middle-aged Brit, made by a middle-aged Brit."

At the same time, the film aimed to satisfy his "inner 12-year-old" – and his nine-year-old son Joe: "One of the biggest reasons for doing this was to make a film my son could see." His devotion to his son could not be clearer. But he and Joe's mother, Kate Winslet (who was picking up a CBE from Buckingham Palace on the day we met), divorced last year and Mendes has since been reported to be in a relationship with the actress Rebecca Hall, daughter of Sir Peter Hall. How much pressure does being in the public eye put on a marriage?

"I don't think it makes a difference to the internal workings of a relationship," he says cautiously. "It is more difficult for women. But people have been very respectful and I think we handled ourselves with dignity which is the important thing. The overriding concern, as always, is for the health and happiness of our children." He sounds, understandably, stilted – as if reading a press release aloud.

Today, Mendes feels "blessed" but adds: "I don't take any of it for granted." After years in America, he is now based in London – and has a house in the country – where he feels "happy and rooted". Has he ever failed at anything? "God, yes – do you want a list? I can't speak a foreign language. I can't type or play golf. I can't cook. And I have not got a perfect track record in the art of conducting relationships with the opposite sex…" And what about as a director? "I have been down some blind alleys and felt I was repeating myself. I did Skyfall to shock and wake myself up. And it has certainly done that – and then some."

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